Living Under a Rock: The Boulder Village of Monsanto

The hillside medieval village of Monsanto was built around a pile of massive granite boulders. The placement of the rocks determined the shapes of the winding streets and the architecture of the stone houses—instead of trying to move the boulders, the villagers used them as walls, floors, and even roofs. From a distance, some of the houses look like they've been crushed by giant falling rocks.

Other than the odd air conditioning unit, plastic chair, and electric lamppost, Monsanto has retained its medieval appearance. It is now home to about 800 people. There are no cars—the preferred mode of transport through the narrow cobbled streets is donkey.